The present invention relates to a mobile communication system that is capable of realizing the use in combination of a wireless local loop (WLL) communication system and a mobile communication system using frequency channel sharing and time slot sharing based on a time-divided multiple access (TDMA) method, or a code division multiple access (CDMA) method, or a time-divided CDMA method.
A mobile communication system mainly comprises for example a mobile vehicle communication apparatus or mobile portable communication apparatus (hereinafter referred to as mobile stations) and base stations that communicate with the mobile stations through radio channels or wireless channels. In mobile communication systems, sometimes a radio frequency spectrum using different radio communication methods is shared between FDMA (frequency division multiple access)/TDMA method and a CDMA method. CDMA methods sharing frequencies between different codes have been performed. In the prior art, the technique in a mobile communication system with time slot sharing in which TDMA signals and time-divided CDMA signals are shared in a same time slot is known. In addition to this, there is a technique in mobile communication systems with time slot sharing, in which TDMA signals and time-divided CDMA signals are commonly used in a same time slot, and with frequency sharing. Furthermore, there is the conventional system that shares a plurality of CDMA signals disclosed in the United State patent U.S. Pat. No. 5,363,403, Spread Spectrum CDMA Subtractive Interference Canceller and Method, by D. L. Schilling et al. However, this US patent does not disclose any method handling time-divided CDMA signals.
In addition, in U.S. Pat. No. 5,511,068, Mobile Communication system capable of transmitting and receiving radio signals obtained by TDMA and CDMA methods without Interference, T. Sato discloses the Adaptive Filter in a time-divided CDMA signal system. However, in this literature, there is no description of frequency sharing of a time-divided CDMA signal and a TDIMA signal in a time slot.
Furthermore, the Japanese laid open publication number JP-A-6-268575 has disclosed a technique in which a receiving level of a radio signal transmitted from mobile stations to base stations is measured by a base station located in an uplink and the base station divides the received uplink signal into groups and each group is assigned into each time slot.
In addition, the Japanese laid open publication number JP-A-8-228375 discloses a technique to handle outer cells and inner cells in a concentric circle, but, there is no explanation about a technique to assign time-divided CDMA radio waves to different time slots inside and outside of a concentric circle zone of a mobile station or a Wireless Local Loop (WLL) station. In addition, in this literature, there is no description about interference in which a large power radio waves generate noise in small power radio waves in the demodulation of the CDMA method or about anti-interference.
As described above, in the prior art, in the conventional mobile communication systems formed; by WLL stations or mobile stations and base stations communicating them through radio wave channels, there is the requirement to expand time slot sharing and frequency channel sharing using different radio communication methods to WLL communication and mobile communication sharing systems performed between TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals.
Furthermore, the prior art entails the problem that it has been necessary to determine the function of the mobile switching station that manages the communication of the entire system in which different transmission power signals are assigned into different time slots when TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals are assigned into a mobile station positioned in a concentric-circle zone in a cell.
Moreover, the prior art entails the problem that operators in different mobile communication systems need to be able to perform a frame synchronization in each system described above.
The present invention is proposed to overcome the above drawbacks in the prior art. It is an object of the present invention to provide a mobile communication system enable TDMA signals or time-divided CDMA signals, and synchronous word identification sharing TDMA signals to perform time slot sharing and frequency sharing. mobile communication system is capable of avoiding the masking of TDMA signals, time-divided CDMA signals, and synchronous word identification TDMA signals by larger power transmission signals provided to mobile stations located in different zones. This is performed in a shared same time slot and frequency channel in which TDMA signals, time-divided CDMA signals, and synchronous word identification sharing TDMA signals are shared. For example, radio waves in a downlink transmitted from the base station are divided into different groups according to the magnitude of the radio wave transmission power. Each of the groups is assigned into a different time slot. It is thereby possible to obtain the mobile communication system that enables the shared use of frame synchronization of the same system by base stations belonging to a plurality of operators and capable of avoiding to mask the weak downlink and uplink radio waves.
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus or mobile portable communications apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK, QGMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. The TDMA signal on a same frequency channel and a same time slot comprises a plurality of signals, and the mobile stations, the WLL stations, the base stations identify each of the TDMA signals by setting a different synchronous word to each of the TDMA signals under the control of the mobile switching centers, and the radio communication is performed by using the time-divided CDMA signals that share the time slots and the frequencies with the TDMA signals or share the time slots with the TDMA signals.
This results in the effect that the time slot and frequency are shared in the TDMA signals and/or the time-divided CDMA signals and/or the synchronous word identification sharing TDMA signals. In addition, in the same time slot and frequency channels in which the TDMA signal, the time-divided CDMA signal, and the synchronous word identification sharing TDMA signal are shared, the masking of radio waves by radio waves of a large transmission power, transmitted to mobile stations located in different zones is avoided. It is thereby possible to reduce communication errors.
According to the present invention, there is provided a mobile communication system in which the mobile switching center comprises a memory. The mobile switching center identifies the WLL station belonging to the base station connected to the mobile switching center, stores radio information about the WLL station and relationship information about station identification information. The mobile switching center uses the relationship information of the WLL station stored in the memory when initiating communication to the WLL station.
According to the present invention, there is provided a mobile communication system in which when completing the radio communication with the WLL station, the mobile switching center updates the relationship information of the WLL station stored in the memory by using relationship information obtained during radio communication.
According to the present invention, there is provided a mobile communication system in which when starting a radio communication with the WLL station, the mobile switching center transmits the relationship information of the WLL station to the base station, the base station receives the relationship information of the WLL station, a transmitter incorporated in the base station controls a transmission power of a radio wave according to a position of the WLL station by using the received relation information of the WLL station, and transmits the radio wave of the controlled transmission power to the WLL station.
According to the present invention, there is provided a mobile communication system in which when starting a radio communication with the WLL station, the mobile switching center controls the transmission power of a radio wave transmitted from the base station connected to the WLL station according to a position of the WLL station by using the relationship information of the WLL station stored in the memory. A time slot is set corresponding to the transmission power of the radio wave.
According to the present invention, there is provided a mobile communication system in which a transmitter incorporated in each of the mobile stations, the WLL stations, and the base stations controls a transmission power of the TDMA signal, that shares a time slot and frequency channel with the time-divided CDMA signal, and the synchronous word identification sharing TDMA signal. Control is performed under the control of the mobile switching center.
According to the present invention, there is provided a mobile communication system in which the mobile switching center classifies the mobile stations and the WLL stations according to many kinds of magnitude of transmission powers of the TDMA signals and the synchronous word identification sharing TDMA signals that share time slots and frequency channels with time-divided CDMA signals, and assigns a different time slot to each classification. This results in an effect in that they are classified into groups according to transmission powers of the time-divided CDMA signal in downlink of the base station, and each group is assigned to different time slot.
According to the present invention, there is provided a mobile communication system in which the mobile switching center classifies the mobile stations and the WLL stations according to many kinds of magnitude of transmission powers of the TDMA signals, assigns a different time slot to each classification, sets a zone in one cell virtually for each classification, and locates the mobile stations and the WLL stations using the TDMA signals and the synchronous word identification signals sharing the time slots and the frequency channels with time-divided CDMA signals in the zone. Furthermore the mobile switching center stores allocation information about the mobile stations and the WLL stations in the memory for controlling.
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK, QGMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. Otherwise in the mobile communication system, a plurality of time-divided CDMA signals and a plurality of TDMA signals share no frequency and share the same time slot. The mobile stations, the WLL stations, and the base stations in the mobile communication system have at least one time-divided CDMA control channel in the time-divided CDMA signal or at least one TDMA control signal in the TDMA signal under the control of the mobile switching center. The time-divided CDMA control channel handles control information of the time-divided CDMA method and control information of the TDMA method simultaneously The TDMA control channel handles the control information of the TDMA method and the control information of the time-divided CDMA method simultaneously.
According to the present invention, there is provided a mobile communication system in which the mobile station or the WLL station transmits and receives the control signal of the time-divided CDMA method and the control signal of the TDMA method and processes information relating the control signal of the time-divided CDMA method and information relating the control signal of the TDMA method simultaneously, and receives the TDMA control channel and the time-divided CDMA control channel under a receiving state of a broadcasting control channel. It selects one of the TDMA control channel and the time-divided CDMA control channel and transmits the control information to the base stations and the mobile switching centers by using the selected control channel. This enables use of the control information through a plurality of control channels among the mobile stations, the WLL stations, and the Base stations.
According to the present invention, there is provided a mobile communication system in which one of the base station and the mobile switching center or both the base station and the mobile switching center transmit and receive the control signal of the time-divided CDMA method and the control signal of the TDMA method and process information relating the control signal of the time-divided CDMA method and information relating the control signal of the TDMA method simultaneously. Otherwise one or both select one of processing of the information relating the control signal of the time-divided CDMA method and processing of the information relating the control signal of the TDMA method.
According to the present invention, there is provided a mobile communication system in which one of the base station and the mobile switching center or both the base station and the mobile switching center transmit and receive the control signal of the time-divided CDMA method and the control signal of the TDMA method and process information relating the control signal of the time-divided CDMA method and information relating the control signal of the TDMA method simultaneously. One or both broadcast information relating a traffic rate of the time-divided CDMA control channel and the TDMA control channel through a broadcasting control channel of the time-divided CDMA control channel and the TDMA control channel. The mobile station or the WLL station selects either the time divided CDMA control channel or the TDMA control channel.
According to the present invention, there is provided a mobile communication system in which one of the base station and the mobile switching center or both the base station and the mobile switching center transmit and receive the control signal of the time-divided CDMA method and the control signal of the TDMA method and process information relating the control signal of the time-divided CDMA method and information relating the control signal of the TDMA method simultaneously. One or both transmit and receive the time-divided CDMA control channel by using one of time frames, and transmit and receive the TDMA control channel by using a following time frame so that the time-divided CDMA control channel and the TDMA control channel are transmitted and received alternately per frame.
According to the present invention, there is provided a mobile communication system comprising a plurality of mobile stations, WLL stations, base stations, and mobile switching centers belonging to different operators. The plurality of mobile switching centers belonging to said all operators select either time slots and frequency channels in a TDMA method or a time-divided CDMA method when the TDMA method and the time-divided CDMA method share time slots forming frames on a time axis, and cells formed by radio waves transmitted by the plurality of base stations belonging to the all operators are overlapped. The mobile stations, the WLL stations, the base stations, and the mobile switching centers belonging to the different operators share information regarding a frame configuration of the time slot and frequency channels of the selected method.
According to the present invention, there is provided a mobile communication system in which each of the plurality of base stations transmits the TDMA control channel or the time-divided CDMA control channel. One base station belonging to one operator interrupts the transmission of the control channel in a time slot while transmitting notice information and so on to the mobile stations or to the WLL stations. That base station receives a control channel from the other base station belonging to the other operator during the interrupted time slot and synchronizes their own time frame with a time frame of the other base station belonging to the other operator.
According to the present invention, there is provided a mobile communication system in which when a base station belonging to an operator working as the standard of the time frame breaks down and interrupts the transmission of the control channel, the plurality of base stations select and use a control channel of the other base station belonging to the other operator as an alternative standard of the time frame.
According to the present invention, there is provided a mobile communication system in which when a base station belonging to an operator working as the standard of the frame breaks down and interrupts the transmission of the control channel, the plurality of base stations select and use a control channel of the other base station belonging to the other operator as an alternative standard of the time frame. The plurality of base stations and the mobile switching centers store the order of the other base stations to be the standard into a memory incorporated in each of the plurality of base stations and the mobile switching centers, and abandon the failed base station as the standard, and newly select the other base station as the standard for frame synchronization according to the order stored in the memory.
According to the present invention, there is provided a mobile communication system comprising mobile stations, WLL stations, a plurality of base stations, and mobile switching centers. Each of the plurality of base stations transmits a TDMA control channel or a time-divided CDMA control signal, and transmits notice information to the base stations or the WLL stations. The plurality of base stations have the function of synchronizing their own frame based on the synchronization information of a frame of other base station. The plurality of base stations may be located so that they do not directly receive radio waves transmitted from other base stations to each other. In this case, the mobile stations or the WLL stations, located at peripheral areas where cells formed by the radio waves transmitted from the plurality of base stations are overlapped, have the function of receiving a plurality of control channels transmitted from the plurality of base stations, measuring time differences among frame synchronization of the plurality of base stations, and transmitting information of the measured time difference to one of, or both of, or the plurality of base stations. The base stations synchronize their own frame with the frame of other base stations based on the transmitted information of the time difference about the frame synchronization. This enables efficient frame synchronization.
According to the present invention, there is provided a mobile communication system in which the plurality of base stations belong to different operator, respectively.
According to the present invention, there is provided a mobile communication system in which even if a WLL station is not calling, said WLL stations are capable of receiving a plurality of control channels transmitted from the plurality of base stations, of measuring the time difference among the frame synchronizations transmitted from the plurality of base stations, and of transmitting the measured information of the time difference to one of, or both of, or the plurality of base stations.
According to the present invention, there is provided a mobile communication system in which when there is no WLL station or no mobile station in the peripheral areas in which the cells formed by the radio waves from the plurality of base stations are overlapped, a supervision station is placed at a position where the radio waves from the plurality of base stations can be received. This supervision station measures the time difference among the frame synchronizations transmitted from the plurality of base stations, and transmits the measured information of the time difference to one of, or both of, or the plurality of base stations.
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus or mobile portable communication apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA QGMSK or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. When mobile switching stations assign time-divided CDMA time slots to concentric zones in peripheral cells, zones in one cell to be assigned to the same time slot are assigned so as not overlap with the zones in the peripheral cells. Thereby, the zones and the time slots are combined properly and the masking of a transmission signal of a small power by a transmission signal of a large power is avoided.
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus or portable communication apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK, QGMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. The mobile stations, the WLL stations, and the base stations under instruction of the mobile switching stations control the sharing of cellular time-divided time slots and a PCS time-divided time slots in a same time-divided time slot so that a guard time of the cellular time-divided time slot is longer than a guard time of the PCS time-divided time slot. Thereby, the zones and the time slots are combined properly, masking a transmission signal of a small power by a transmission signal of a large power is avoided and the data communication is performed.
According to the present invention, there is provided a mobile communication system in which the cellular time-divided time slots is a cellular time-divided CDMA time slot, and the PCS time-divided time slot is a PCS time-divided CDMA time slot. The mobile stations, the WLL stations, and the base stations under instruction of the mobile switching stations control the sharing of the cellular time-divided CDMA time slot and the PCS time-divided CDMA time slot in the same time-divided time slot so that a guard time of the cellular time-divided CDMA time slot is longer than a guard time of the PCS time-divided CDMA time slot.
According to the present invention, there is provided a mobile communication system in which the cellular time-divided time slot is a cellular TDMA time slot, and the PCS time-divided time slot is a PCS TDMA time slot. The mobile stations, the WLL stations, and the base stations under instruction of the mobile switching stations control the sharing of the cellular TDMA time slot and the PCS TDMA time slot in the same time-divided time slot so that a guard time of the cellular TDMA time slot is longer than a guard time of the PCS TDMA time slot.
According to the present invention, there is provided a mobile communication system in which the cellular time-divided time slot is a cellular time-divided CDMA time slot and a cellular TDMA time slot, and the PCS time-divided time slot is a PCS time-divided CDMA time slot and a PCS TDMA time slot The mobile stations, the WLL stations, and the base stations under instruction of the mobile switching stations control the sharing of the cellular time-divided CDMA time slot and the cellular TDMA time slot and the PCS time-divided CDMA time slot and the PCS time-divided time slot in the same time-divided time slot so that a guard time of the cellular time-divided time slot is longer than a guard time of the PCS time-divided time slot.
According to the present invention, there is provided a mobile communication system comprising mobile stations of a plurality of mobile vehicle communication apparatus or mobile portable communication apparatus, semi-fixed WLL stations, at least one base station, and mobile switching centers connected to the base station. Radio communication among the above is performed based on FDMA or multi-carrier TDMA, or CDMA method, or time-divided CDMA method which are digital modulation methods such as FSK, BPSK, QPSK, QDPSK, p/4-DQPSK, QAMSK, QGMSK. The mobile communication system shares time slots and frequency channels having shared channels which are time-divided CDMA signal channels that share time slots and frequencies on a frequency axis with FDMA/TDMA digital signals. The mobile station uses TDMA signals or time-divided CDMA signals of different time slots in communication to the plurality of base stations The mobile station measures a transmitting time of radio-waves sent by the mobile station, prior to a time position of a head of the time slot according to time slot information obtained from one base station The mobile station then measures a time difference between a time of a head of a received radio wave from one base station and a time of a head of a received radio wave from the plurality of base stations, and the mobile switching centers store information regarding the measured time difference. When communicating with one base station, the mobile stations receive information regarding the time difference from the mobile switching centers and obtain the time information regarding the transmitting time that is a time prior to the head position of the time slot, at which the radio wave will be transmitted. Thereby, a proper time position of a time slot is always designated and controlled.
According to the present invention, there is provided a mobile communication system in which the information of the time difference is stored in a memory in each of the plurality of mobile switching centers. Thereby, the same information of time difference is shared among the plurality of mobile switching centers and a proper time position of a time slot is always designated and controlled.